PHP code to count the number of people online combined with mysql to count the number of people online

CREATE TABLE ccol(
id integer not null auto_increment, #Recorded ID
ip char(15) not null, #Visitor’s IP address
dtstamp datetime not null, #Last access time
uri char(255 ), #URI requested by the visitor
primary key (id)
);

Then, write the php code for statistics

/*
File: ccol.php
Purpose: To count the number of people browsing online at the same time
edit: bbs.it-home.org
*/
＄duration=1800 ;
require "db.php"; //Prepare yourself, database access class
//Contains DBSQL
＄ccol=new dbSQL;
＄ccol->connect();
＄ccol->query("DELETE FROM ccol WHERE (UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(dtstamp))>＄duration");
//Delete records older than half an hour
＄ccol->query("SELECT * FROM ccol WHERE ip='＄REMOTE_ADDR '");
//Determine whether the current IP exists in the table
if (＄ccol->nf())//Yes?
{
＄ccol->next_record();//Move down the pointer of the found record array
＄id=＄ccol->f('id');
＄ccol->query("UPDATE ccol SET dtstamp=now(), uri='＄REQUEST_URI' WHERE id=＄id");
//Set the last access time and access page
}
else//No
{
＄ccol->query("INSERT INTO ccol VALUES (0, '＄REMOTE_ADDR', now(), '＄REQUEST_URI')");
}
＄ccol->query("SELECT COUNT(*) AS ccol FROM ccol WHERE (UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(dtstamp))<=＄duration");
//Find the records within half an hour, the following WHERE clause is optional--out of time Has been deleted
＄ccol->next_record()
echo "Number of people online:", ＄ccol->f('ccol');
＄ccol->free_result();
?>

call method and call this program on every page of the site. For example:

--index.php
...